The low temperature poly-silicon (LTPS) technology is the manufacture technology of the new generation TFT substrate. The most significant difference from the traditional amorphous silicon (a-Si) is that the response speed of the LTPS display is faster and possesses advantages of high brightness, high resolution and low electrical power consumption. The poly-silicon (poly-Si) possesses excellent electrical property, and better drive ability to the active matrix organic light emitting diode (AMOLED). Thus, the AMOLED display back plate based on the low temperature poly-silicon technology has been widely utilized at present.
The present manufacture method of the LTPS TFT substrate mainly comprises the following steps:
Step 1, as shown in FIG. 1, providing a substrate 100, wherein the substrate 100 comprises a drive TFT area and a display TFT area, and depositing a buffer layer 110 on the substrate 100;
Step 2, as shown in FIG. 2, depositing an amorphous silicon layer on the buffer layer 110 and implementing an excimer laser annealing process to the amorphous silicon layer to make the amorphous silicon layer crystallized and converted to be a poly-silicon layer 130 after excimer laser annealing pretreatment;
Step 3, as shown in FIG. 3, patterning the poly-silicon layer 130 to obtain a first poly-silicon section 140 in the drive TFT area and a second poly-silicon section 150 in the display TFT area which are alternately spaced;
Step 4, depositing a gate isolation layer 160 on the first poly-silicon section 140, the second poly-silicon section 150 and the buffer layer 110;
Step 5, depositing and patterning a first metal layer on the gate isolation layer 160, and forming a first gate 170 and a second gate 180 respectively above the first poly-silicon section 140 and the second poly-silicon section 150 and corresponding thereto;
Step 6, depositing an interlayer insulation layer 190 on the gate isolation layer 160, the first gate 170 and the second gate 180, and forming a first via 200 and a second via 200′ in the interlayer insulation layer 190 and the gate isolation layer 160 respectively above the first poly-silicon section 140 and the second poly-silicon section 150 and corresponding thereto; and
Step 7, as shown in FIG. 4, depositing and patterning a second metal layer on the interlayer insulation layer 190, and respectively forming a first source/drain 210 in the drive TFT area and a second source/drain 220 in the display TFT area, and the first source/drain 210 contacts with the first poly-silicon section 140 through the first via 200, and the second source/drain 220 contacts with the second poly-silicon section 150 through the second via 200′.
In the above process, the excimer laser annealing (ELA) technology utilizes transient pulses of laser to irradiate on the surface of the amorphous silicon layer to be melted and recrystallized. The AMOLED driving requires a drive TFT and a display TFT. The drive TFT demands larger lattice and thus higher electron mobility is required. The display TFT needs efficient electron mobility and uniformity of the electrical current. Accordingly, the OLED element can uniformly illuminate.
However, the ELA crystallization technology according to prior art cannot achieve effective control to the uniformity of the lattices and the crystallization direction of the lattices. The distribution of crystallization condition in the entire substrate is extremely non-uniform and results in that the long distance of the display effect is not uniform.